Food habits of juvenile tuskfishes (Choerodon schoenleinii and C. anchorago) in relation to food availability in the shallow waters of Ishigaki Island, Southwestern Japan

The gut contents of juvenile tuskfishes Choerodon schoenleinii and C. anchorago changed in fish with a size of a parts per thousand yen25 mm total length (TL) in shallow waters of Ishigaki Island, southwestern Japan. Epiphytic copepods were an important food source for individuals of < 25 mm TL for both species. The taxonomic compositions of copepods differed between the two species, and this difference may be related to differences in the biomass of brown algae during different seasons of recruitment. C. schoenleinii were recruited in shallow waters during March and April, when there is a substantial biomass of brown algae bearing an abundance of epiphytic harpacticoids. Brown algae serve as a feeding habitat as well as a shelter for C. schoenleinii. C. anchorago first appeared in May and June after most of the brown algal biomass had been shed, and they fed on calanoids as well as harpacticoids epiphytically associated with seagrasses. In two Choerodon species of a parts per thousand yen25 mm TL, food habits grew more diverse and included larger animals such as gammarids, isopods, cumaceans, decapods, and molluscs. These results indicate that brown algae are important providers of food items for early-stage juveniles of C. schoenleinii.